(1) Technical Field
This invention relates to hoists or cranes capable of lifting heavy objects and moving the same. (2) Description of the Prior Art
Prior art devices of this type have relied on a variety of different structures for use on the ground and some mountable in trucks. See for example U.S. Pat. Nos. 3,521,860, 2,947,425 and 4,069,922.
In U.S. Pat. No. 2,947,425 a hydraulic hoist is disclosed that is mounted in a truck bed having a vertical stationary post with a movable sleeve thereon to which is secured a piston and cylinder assembly supporting a horizontally extending arm.
In U.S. Pat. No. 3,521,860, a knock down hoist is shown which is typical of a hoist design, having a U-shaped support frame and a removable vertical support member with a pivoted arm at its uppermost point. A hydraulic piston and cylinder is secured to the support member and the arm.
In U.S. Pat. No. 4,069,922 a portable crane with a hoist is disclosed which is mounted in a truck bed. This device requires an outrigger support foot to stabilize the crane and hoist. The base is secured to the truck with the uppermost portion rotatable therein.
Applicant's device can be mounted in a truck to the truck frame and utilizes a three-piece structure allowing a portion of the main vertical support member to be used as a horizontal tow arm extending outwardly of the truck when mounting therein.